An image displaying device such as a general television or a general display device has been widely used. Recently, it is an important issue to improve the quality of the image frame in order to develop the image displaying technology. With increasing development of science and technology, the image displaying device is gradually developed from the early cathode ray tube display to the today's liquid crystal display (LCD). Nowadays, since the basic image displaying quality is significantly improved and the overall volume of the image displaying device is reduced, the applications of the displaying technology are broadened. However, the LCD displaying technology still has some drawbacks.
As known, the liquid crystal molecule itself is not luminous. Consequently, the LCD display uses a backlights module (e.g., LED) as a light source and controls the liquid crystal arrangement of the liquid crystal panel to produce the illuminated image.
Generally, the liquid crystal panel is light-transmissible, and the liquid crystal molecules are arranged in an array. When the liquid crystal molecules are operated under the polarizing plate, the combination of the brightness and the corresponding color exhibits the image contents (e.g., characters or symbols). Moreover, as the voltage applied to the polarizing plate is controlled, the polarity of the liquid crystal molecules is correspondingly changed. Consequently, the arrangement of the liquid crystal molecules is adjusted. Since the liquid crystal molecules are correspondingly rotated, the transmittance of the light beam from the backlight source is changed.
Regardless of the materials, operating environments or the use practices of the LCD screen, the voltage between the two electrodes of the polarizing plate is subjected to a tiny change after the image shown on the LCD screen has been kept unchanged for a certain time period. Generally, as the time period of showing the same image frame on the LCD screen is increased, the charges retained between the two electrodes result in the gradual accumulation of the voltage. Under this circumstance, the liquid crystal molecules are suffered from variation. Due to the variation, an image sticking problem occurs. For example, after the screen content is refreshed to generate a new frame, a portion of the old content of the original image frame is also shown on the screen.
Normally, in case that the image is continuously changed, the image sticking problem is not generated. However, in some situations, a specified image frame has to be shown on the screen for a long time. For example, the industrial monitoring message, the news channel logo or the medical workstation bed message needs to be shown on the screen for a long time.
For solving the image sticking problem, it is necessary to effectively release the accumulated voltage between the two electrodes. Conventionally, some approaches are disclosed to solve the image sticking problem. In accordance with a conventional approach, the same image frame is not shown on the screen for a long time. In accordance with another conventional approach, the frame shown on the screen is automatically switched after a specified time interval. For example, a screen saver program is executed. In accordance with another conventional approach, the circuitry layer is designed to dynamically adjust the voltage or adjust the discharging time sequence in order to release the residual charges quickly. In accordance with another conventional approach, the manufacturing process and the material of the liquid crystal panel are improved.
However, the associated applications (e.g., the above approaches) still have some drawbacks. For example, in some approaches, the image block to be maintained for a long time is possibly interfered by a meaningless frame. Moreover, the improvement in the hardware component increases the fabricating and searching cost. Therefore, the conventional displaying technology needs to be further improved.